It is estimated that the 2870 miles of railroads finished in New England have cost $132,000,000,—which gives an average of nearly $46,000 per mile. In the Middle States, where the natural obstacles are somewhat less, the average expense per mile of the railroads already built is not far from $40,000. Those now in course of completion—as the Baltimore & Ohio Railroad, Pennsylvania Central, and other lines, the routes of which cross the Alleghany range of mountains—will probably require a larger proportionate outlay, owing to the heavy expense of grading, bridging, and tunnelling. In those States where land has become exceedingly valuable, the cost of extinguishing private titles to the real estate requires, and the damages to property along the routes form, a heavy item in the account of general expenses of building railroads. In the South and West the case is reversed: there the proprietors along the proposed line of a road are often willing and anxious to give as much land as may be needed for its purposes, and accord many other advantages in order to secure its location through or in the vicinity of their possessions. In the States lying in the valleys of the Ohio and Mississippi the cost of grading, also, is much less than at the eastward. Where the country is wooded, the timber can be obtained at the mere cost of removing it from the track; and through prairie districts Nature seems to have prepared the way for these structures by removing every obstacle from the surface; while fine quarries of stone are to be found in almost every region. These favorable circumstances render the estimate of $20,000 per mile in all the new States safe and reliable. The primary design of nearly all the great lines of railway in the United States has been to connect the sea-coast with the distant interior, to effect which object it was necessary to cross the Alleghanies, which intersect every line of travel diverging to the West from the great commercial cities of the seaboard. The Eighth Census (1860), continuing the line, makes this addition to that of the Seventh:— Previous to the commencement of the last decade, only one line of railroad has been completed between tide-water and the great interior basins of the country, the products of which now perform so important a part in our internal and foreign commerce. Even this line, formed by the several links that now compose the New York Central Road, was restricted in the carriage of freight except on the payment of canal tolls in addition to other charges for transportation, which restriction amounted to a virtual prohibition. The commerce resulting from our railroads consequently has been, with comparatively slight exceptions, a creation of the last decade.